What does "no more recursive clients: quota reached" mean?

When you see the "quota reached" message, you have reached the limit for outstanding recursive queries that the recursive name server allows.

When a recursive name server receives queries and it is not authoritative, the recursive name server needs to ask other name servers to get answers for those queries. Until the recursive name server learns the answers, the recursive queries remain outstanding.

The recursive name server puts a limit on how many outstanding recursive queries it allows; this number is limited by the configuration setting at member DNS properties. The default value for outstanding recursive queries is 1000.

As stated, if you are seeing the "quota reached" message, you have reached the limit for outstanding recursive queries that the server allows. You may need to increase the limit.

If it is not normal to see that many queries in your environment, then some other issue or issues may have caused a relatively large number of queries. Examples of these other issues include DNS resolution issues due to connectivity or some badly-behaving clients that are sending unnecessary queries. You must investigate and resolve these other issues before increasing the limit for outstanding recursive queries.
If you find that the outstanding recursive queries are genuine traffic and you find no other issues, you can increase the limit for the outstanding recursive queries allowed on the recursive name server-- as long as the number is not too high for the DNS server platform.
If you want to increase the number of outstanding recursive queries on the recursive name server, confirm that you have adequate memory available for that number of outstanding recursive queries and for other services that are configured on the same server. Every recursive query can take about 20 kilobytes.

To increase the limit for outstanding recursive queries:

1. From the Data Management tab, select the DNS tab and click the Members tab > member check box > Edit icon.
2. In the Member DNS Properties editor, click Toggle Advanced Mode.
3. When the additional tabs appear, click the Advanced subtab of the Queries tab.
4. Select the Limit number of recursive clients to option and enter a number.
5. Save the configuration and click Restart if it appears at the top of the screen.